Mice and Their Wheels

So, some good news from our animal-watching friends. According to a paper in Proceedings of the Royal Society, Biological Sciences department, wild mice like to run on wheels, in pretty much the same ways that regular old domesticated mice do, so doctors Johanna H Meijer and Yuri Robbers have some payoff for all their mouse-watching. It hasn’t all been about making mice nervous about being stared at; those are just bonuses.

According to their research wild mice run pretty much the same way domestic mice do: the mouse comes out, pokes at the wheel a little, then hops on and starts running until it starts squeaking. Then the mouse keeps running until the squeaking drives somebody crazy, and that somebody comes out and dabs a little vegetable oil on the axle. Once that’s done, the mouse is overjoyed because, hey, vegetable oil. That stuff doesn’t grow on trees. I guess except palm oil. And banana oil. Maybe also oak oil. Or for that matter tuna oil, for fish that have been lifted into trees, perhaps by a waterspout or by a practical joker or by the efforts of a daring fish explorer. I guess the important thing is, vegetable oil on the axle. Once that’s there, the mouse is delighted because steel slathered in vegetable oil is delicious, and the mouse can lick it all off, giving much-needed calories and a refreshing taste sensation before going back to running and driving people crazy by their squeaking. There’s nothing about this that requires domestication, is there? Just fish.

Mouse wheel-running, the paper says, is done in bursts lasting from under one minute to as much as eighteen minutes, which I think is interesting because it means a mouse can plausibly run a wheel for longer than the half-life of a neutron outside an atomic nucleus. I can picture mice puttering along on the wheel and chuckling at a pair of free neutrons, telling them, “by the time I get off this wheel at least one of you is gonna be gone.” So now you know why back in middle school I was the kid people wouldn’t play Dungeons and Dragons with.

The average wheel-running speed for a mouse in the wild is about 1.3 kilometers per hour, while that in the lab is 2.3 kph. The maximum speed of a wild mouse, though, was about 5.7 kph, while laboratory mice topped out at 5.1. This means something, although you have to divide all those figures by 1.6 to know what they mean in the United States.

The researchers got videos of different animals running the wheel. There were a couple of rats who went running, and some shrews. There were some frogs, too, raising the question of wait a minute how can a frog run on a wheel? Surely they were hopping the wheel instead, and that should’ve been a data point for the paper about whether wild mice will get their hopping done on wheels. But more surprising and I swear this is exactly what they say, there were incidents of slugs and even a snail getting on the wheel. A snail! This, this is what Turbo is doing to screw up the ecosystem.

They have video of the slug running on the wheel, too. It’s the third video, twenty seconds of time at http://rspb.royalsocietypublishing.org/content/281/1786/20140210/suppl/DC1 and as you can see at a glance, nothing happens in it. But if you zoom the video up to full-screen, and if you get a bigger screen, you can see the wheel is turning a wee tiny little bitty bit, at about the same rate that Pluto rolls around the solar system, only with a slug. Why do they not have the snail video? Did they feel embarrassed on the snail’s behalf?

A caption to some of the photos mentions that there were birds that visited the wheel, but none of them were spotted running. Superficially this is a very frog-like situation since I’d expect birds to be flying the wheel, but if they’re flying, they don’t even need the wheel. But birds can run when the spirit so moves them, such as when they need to complete a Fun Run which they entered because of the attractive rhyme such offer. That no birds were observed to run indicates a shortage of the fun in outdoor spaces near campus. Maybe the birds are worried about their quals.

I wonder if now that we know mice like wheels there’s any research under way to see what wheels feel about mice.

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